Quantum correlations in light interacting with mechanical systems arise as a consequence of quantum measurement backaction. We have developed a method to extract small quantum correlations on light that has interacted with a nano-optomechanical system even when the nano-optomechanical system is strongly coupled to its ambient, room-temperature environment. The scale of these backaction-induced correlations is related to the scale of mechanical zero-point motion through a Heisenberg measure-disturbance uncertainty relation. We use the scale of the correlations to absolutely calibrate the optically measured thermal, Brownian motion of the nanomechanical system, demonstrating a path toward a wide-range, on-chip, optically based, primary, i.e. “self-calibrating”, temperature standard. We will present our measurements of quantum backaction at room temperature and will report current progress on this on-going project in quantum metrology.